const Stats = (() => {
  async function init() {
    await loadStats();
  }

  async function loadStats() {
    const content = document.getElementById('stats-content');
    content.innerHTML = '<div class="loading">Loading stats...</div>';

    try {
      const stats = await API.getStats();
      renderStats(stats);
    } catch (e) {
      content.innerHTML = '<div class="error-msg">Error loading stats: ' + escHtml(e.message) + '</div>';
    }
  }

  function renderStats(stats) {
    const content = document.getElementById('stats-content');
    let html = '';

    // Summary totals
    if (stats.total !== undefined || stats.totalDistance !== undefined) {
      const totalDist = stats.total?.distance || stats.totalDistance || 0;
      const totalTracks = stats.total?.count || stats.trackCount || 0;
      html += `<div class="stats-section">
        <h3>Total</h3>
        <div class="stat-row">
          <span class="stat-label">Tracks</span>
          <div class="stat-bar-wrap"><div class="stat-bar" style="width:100%"></div></div>
          <span class="stat-value">${totalTracks}</span>
        </div>
        <div class="stat-row">
          <span class="stat-label">Distance</span>
          <div class="stat-bar-wrap"><div class="stat-bar" style="width:100%"></div></div>
          <span class="stat-value">${formatDistance(totalDist)}</span>
        </div>
      </div>`;
    }

    // By year
    if (stats.byYear && stats.byYear.length > 0) {
      const maxDist = Math.max(...stats.byYear.map(s => s.distance || 0));
      html += '<div class="stats-section"><h3>By Year</h3>';
      for (const s of stats.byYear) {
        const pct = maxDist > 0 ? ((s.distance || 0) / maxDist * 100) : 0;
        html += `<div class="stat-row">
          <span class="stat-label">${s.year}</span>
          <div class="stat-bar-wrap"><div class="stat-bar" style="width:${pct.toFixed(1)}%"></div></div>
          <span class="stat-value">${formatDistance(s.distance)}</span>
        </div>`;
      }
      html += '</div>';
    }

    // By month (last 24 months)
    if (stats.byMonth && stats.byMonth.length > 0) {
      const recent = stats.byMonth.slice(-24);
      const maxDist = Math.max(...recent.map(s => s.distance || 0));
      html += '<div class="stats-section"><h3>By Month (last 24)</h3>';
      for (const s of recent) {
        const pct = maxDist > 0 ? ((s.distance || 0) / maxDist * 100) : 0;
        const label = `${s.year}-${String(s.month).padStart(2, '0')}`;
        html += `<div class="stat-row">
          <span class="stat-label">${label}</span>
          <div class="stat-bar-wrap"><div class="stat-bar" style="width:${pct.toFixed(1)}%"></div></div>
          <span class="stat-value">${formatDistance(s.distance)}</span>
        </div>`;
      }
      html += '</div>';
    }

    // By week (last 52 weeks)
    if (stats.byWeek && stats.byWeek.length > 0) {
      const recent = stats.byWeek.slice(-52);
      const maxDist = Math.max(...recent.map(s => s.distance || 0));
      html += '<div class="stats-section"><h3>By Week (last 52)</h3>';
      for (const s of recent) {
        const pct = maxDist > 0 ? ((s.distance || 0) / maxDist * 100) : 0;
        const label = `${s.year}-W${String(s.week).padStart(2, '0')}`;
        html += `<div class="stat-row">
          <span class="stat-label">${label}</span>
          <div class="stat-bar-wrap"><div class="stat-bar" style="width:${pct.toFixed(1)}%"></div></div>
          <span class="stat-value">${formatDistance(s.distance)}</span>
        </div>`;
      }
      html += '</div>';
    }

    if (!html) {
      html = '<div class="empty-list">No tracks yet. Upload some GPX files to see stats.</div>';
    }

    content.innerHTML = html;
  }

  return { init, loadStats };
})();